Records communication from all extensions using
mysqlnd to the specified log file.

The format of the directive is mysqlnd.debug =
"option1[,parameter_option1][:option2[,parameter_option2]]".

The options for the format string are as follows:

A[,file] - Appends trace output to specified file. Also ensures
that data is written after each write. This is done by closing
and reopening the trace file (this is slow). It helps ensure a
complete log file should the application crash.

a[,file] - Appends trace output to the specified file.

d - Enables output from DBUG_<N> macros for the current
state. May be followed by a list of keywords which selects
output only for the DBUG macros with that keyword. An empty list
of keywords implies output for all macros.

f[,functions] - Limits debugger actions to the specified list of
functions. An empty list of functions implies that all functions
are selected.

F - Marks each debugger output line with the name of the source
file containing the macro causing the output.

i - Marks each debugger output line with the PID of the current
process.

L - Marks each debugger output line with the name of the source
file line number of the macro causing the output.

n - Marks each debugger output line with the current function
nesting depth

o[,file] - Similar to a[,file] but overwrites old file, and does
not append.

O[,file] - Similar to A[,file] but overwrites old file, and does
not append.

t[,N] - Enables function control flow tracing. The maximum
nesting depth is specified by N, and defaults to 200.

x - This option activates profiling.

m - Trace memory allocation and deallocation related calls.

Example:

d:t:x:O,/tmp/mysqlnd.trace

Note:

This feature is only available with a debug build of PHP. Works
on Microsoft Windows if using a debug build of PHP and PHP was
built using Microsoft Visual C version 9 and above.

Defines which queries will be logged. The default 0, which disables logging.
Define using an integer, and not with PHP constants. For example, a value of
48 (16 + 32) will log slow queries which either use 'no good index'
(SERVER_QUERY_NO_GOOD_INDEX_USED = 16) or no index at all (SERVER_QUERY_NO_INDEX_USED = 32).
A value of 2043 (1 + 2 + 8 + ... + 1024) will log all slow query types.

mysqlnd and the MySQL Client Library,
libmysqlclient use different networking APIs.
mysqlnd uses PHP streams, whereas
libmysqlclient uses its own wrapper around the
operating level network calls. PHP, by default, sets a read
timeout of 60s for streams. This is set via
php.ini,
default_socket_timeout. This default applies to
all streams that set no other timeout value.
mysqlnd does not set any other value and
therefore connections of long running queries can be disconnected
after default_socket_timeout seconds resulting
in an error message "2006 - MySQL Server has gone
away". The MySQL Client Library sets a default timeout of
365 * 24 * 3600 seconds (1 year) and waits for other timeouts to
occur, such as TCP/IP timeouts. mysqlnd now
uses the same very long timeout. The value is configurable through
a new php.ini setting:
mysqlnd.net_read_timeout.
mysqlnd.net_read_timeout gets used by any
extension (ext/mysql,
ext/mysqli, PDO_MySQL) that
uses mysqlnd. mysqlnd tells
PHP Streams to use mysqlnd.net_read_timeout.
Please note that there may be subtle differences between
MYSQL_OPT_READ_TIMEOUT from the MySQL Client
Library and PHP Streams, for example
MYSQL_OPT_READ_TIMEOUT is documented to work
only for TCP/IP connections and, prior to MySQL 5.1.2, only for
Windows. PHP streams may not have this limitation. Please check
the streams documentation, if in doubt.

mysqlnd.net_cmd_buffer_sizelong

mysqlnd allocates an internal command/network
buffer of mysqlnd.net_cmd_buffer_size (in
php.ini) bytes for every connection. If a
MySQL Client Server protocol command, for example,
COM_QUERY ("normal" query), does
not fit into the buffer, mysqlnd will grow the
buffer to the size required for sending the command. Whenever the
buffer gets extended for one connection,
command_buffer_too_small will be incremented by
one.

If mysqlnd has to grow the buffer beyond its
initial size of mysqlnd.net_cmd_buffer_size
bytes for almost every connection, you should consider increasing
the default size to avoid re-allocations.

The default buffer size is 2048 bytes in PHP 5.3.0. In later
versions the default is 4096 bytes.

It is recommended that the buffer size be set to no less than 4096
bytes because mysqlnd also uses it when reading
certain communication packet from MySQL. In PHP 5.3.0,
mysqlnd will not grow the buffer if MySQL sends
a packet that is larger than the current size of the buffer. As a
consequence, mysqlnd is unable to decode the
packet and the client application will get an error. There are
only two situations when the packet can be larger than the 2048
bytes default of mysqlnd.net_cmd_buffer_size in
PHP 5.3.0: the packet transports a very long error message, or the
packet holds column meta data from
COM_LIST_FIELD
(mysql_list_fields() and the meta data come
from a string column with a very long default value (>1900 bytes).

As of PHP 5.3.2 mysqlnd does not allow setting buffers smaller
than 4096 bytes.

The value can also be set using mysqli_options(link,
MYSQLI_OPT_NET_CMD_BUFFER_SIZE, size).

mysqlnd.net_read_buffer_sizelong

Maximum read chunk size in bytes when reading the body of a MySQL
command packet. The MySQL client server protocol encapsulates all
its commands in packets. The packets consist of a small header and
a body with the actual payload. The size of the body is encoded in
the header. mysqlnd reads the body in chunks of
MIN(header.size, mysqlnd.net_read_buffer_size)
bytes. If a packet body is larger than
mysqlnd.net_read_buffer_size bytes,
mysqlnd has to call read()
multiple times.

The value can also be set using mysqli_options(link,
MYSQLI_OPT_NET_READ_BUFFER_SIZE, size).

Clients can either omit setting a public RSA key, specify the key through
this PHP configuration setting or set the key at runtime using
mysqli_options(). If not public RSA key file is
given by the client, then the key will be exchanged as part of the
standard SHA-256 Authentication Plugin authentication procedure.

mysqlnd.fetch_data_copylong

Enforce copying result sets from the internal
result set buffers into PHP variables instead of using the default
reference and copy-on-write logic. Please, see the
memory management implementation notes
for further details.

Copying result sets instead of having PHP variables reference
them allows releasing the memory occupied for the PHP variables earlier.
Depending on the user API code, the actual database quries and the
size of their result sets this may reduce the memory footprint
of mysqlnd.

Do not set if using PDO_MySQL. PDO_MySQL has not yet been updated to support
the new fetch mode.